1. Field of the Invention
This invention relates to an iodophor and more particularly relates to a polyurethane sponge containing the iodophor and release of iodine therefrom.
2. Background
Iodine is a well-known germicide with activity against a wide range of bacteria and viruses, and much effort has been directed to finding satisfactory vehicles for its administration. Compounds which form complexes with iodine, such a polyvinylpyrrolidone (PVP) and surfactants have been used. The term iodophor is a conventional designation for these iodine-containing complexes.
Polyurethane foams are disclosed as iodophors by Shelanski et al. in U.S. Pat. No. 3,235,446. In the Shelanski et al. invention, a surfactant having hydroxyl end groups reacts with a diisocyanate and becomes part of the polyurethane chain. The Shelanski polyurethane foam complexes iodine, and, when dry releases into water considerably less iodine than originally complexed.
A polyurethane foam which complexes iodine and PVP is disclosed by LeVeen et al. in U.S. Pat. No. 4,381,380. LeVeen et al. reports that the complexed iodine is slowly dissociable from the foam.
Cantor et al., in U.S. Pat. No. 4,017,407 discloses a solid PVP iodophor containing a compatible anionic or nonionic surfactant
Globus, in U.S. Pat. No. 4,873,354, discloses a stable complex of iodine with a polyethylene glycol ester of an alkylarylsulfonic acid. In the Globus disclosure, iodine serves a dual role as a germicide in the iodophor and as a catalyst for the esterification. About one half of the iodine used is available as the germicide.
Iodophors impregnated into a sponge are often mated with a scrub and used for germicidal cleansing or scrubbing. Often, such implements are included in a kit of materials which may also include other items useful for patient preparation, such as towels, gloves and the like. Problems often arise in use of iodine as a germicide. A typical iodophor product is provided and used in the presence of water. Iodine and water undergo a well known but complex series of reactions leading, among other species, to iodide ions and hydrogen ions. The production of hydrogen ions may reduce the pH of a topical iodine preparation enough to cause skin irritation and discomfort to the user. Loss of iodine titer causes an additional problem of assuring that the iodine content of a composition does not fall below the stated concentration on the label during its time on the shelf.
Another problem arises when the iodophor is used with a polyurethane foam sponge. Iodine complexes strongly with polyurethane, and any iodine which is not released from the polyurethane complex is not available as germicide.
Accordingly, a variety of approaches has focused on ways to stabilize the iodine concentration in an iodophor-iodine complex. U.S. Pat. No. 4,271,149 to Winicov et al. discloses a germicidal iodine composition of stabilized iodine concentration. The composition contains an organic material, iodine, iodide ion and iodate ion and is maintained at a pH of from 5 to 7 wherein the iodide and iodate react in the presence of hydrogen ions to replenish iodine lost during storage.
U.S. Pat. No. 4,113,857 to Shetty discloses a method to stabilize a preformed iodophor-iodine complex by adding an oxidizing agent, such as iodate ion, and to prepare a complex by reacting an iodophor, such as providone, with iodate and iodide ions.
An iodine surfactant germicidal cleansing composition is disclosed in U.S. Pat. No. 4,597,975 to Woodward et al. In the Woodward et al. composition, low concentrations of iodine are stabilized as the triiodide salt by complexing with an amine oxide surfactant. When solubilized by excess amine oxide, the triiodide salt has a very low iodine vapor pressure and high germicidal activity.
LeVeen et al. in U.S. Pat. No. 5,000,749 discloses a contraceptive sponge containing iodine in which the iodine is complexed to the polyurethane and is slowly liberated over many days.
Although the above disclosures have improved iodine and iodophor stability, there remains a need for further improvement, particularly when the iodine is used with a polyurethane during a prolonged shelf time. It is toward fulfillment of this need that the present invention is directed.